Proehl: How long does a patent last?
"The tenth and last question in the series of questions regarding patents is: How long does a patent last?
The term of a utility patent begins the day the patent is issued and has the potential to last for 20 years from the earliest filing date accorded to the patent application that became the patent. In order for the patent to remain in effect for the entire potential term, the patent owner must periodically pay a maintenance fee to the U.S. Patent and Trademark Office (USPTO). Payment of three maintenance fees is typically required for the full 20-year term."
